Enhancing the electrochemical performance of supercapacitor electrodes via mixed morphology: A study of nanosphere growth on nanowires of Fe₂PO₅

This study explores the morphological evolution of Fe₂PO₅ nanowires decorated with nanospheres through varying the FeSO₄ to NH₄H₂PO₄ molar ratio. The synthesized sample was analyzed through X-ray diffraction spectroscopy and high-resolution X-ray photoelectron spectroscopy, affirming the successful formation of Fe₂PO₅. Further investigation into morphological alterations was conducted through scanning electron microscopy. The intricacies of the reaction system were explored to determine the kinetic control aspects and the ‘nucleation–aggregation–recrystallization’ mechanism underlying the formation process. Our findings reveal that the optimized Fe₂PO₅ sample displays 3D nanospheres grown on 1D nanowires. This distinctive configuration substantially increased surface area, augmented electrical conductivity, and expedited ion transport. These attributes culminate in the exceptional specific capacitance of 6115 mF/cm² at a current density of 2 mA/cm². The practical utility of Fe₂PO₅ is exemplified through the fabrication of a supercapacitor device, where Fe₂PO₅ serves as the positive electrode, complemented by activated carbon as the negative electrode. The resultant device demonstrates commendable specific capacitance (329.60 mF/cm²) and energy density of 0.103 mWh/cm² at power density of approximately 0.75 mW/cm². The distinctive 1D/3D morphology of Fe₂PO₅ engenders several advantages that include expansive surface area at the electrode/electrolyte interface, abbreviated ion diffusion pathways, accelerated charge/discharge rates, elevated electrical conductivity, and reinforced mechanical properties. Collectively, these attributes position Fe₂PO₅ as a promising candidate for supercapacitor electrodes.